Abstract
This paper is a part of series of experiments concerning the effect of fertilizers applied to the rice plant on the growth of the rice stem borer larvae. Two kinds of rearing experiments were undertaken to make clear the relation between the phosphorus fertilizer and the growth of borer larvae.
In the first experiment, the larvae were reared in a greenhouse using the rice plants cultured in soil to which different quantities of the phosphorus fertilizer (calcium super phosphate) had been supplied. After rearing for 30 days, it was observed that the growth of the larvae was not affected by supplying phosphorus fertilizer to the rice plant. There were also no remarkable differences on the growth-pattern and chemical compositions in the rice plants cultured with high and low phosphorus levels.
In the second experiment, the larvae were reared with sterilized rice stems (borer zone) in flasks under aseptic conditions as described in the previous papers.
Somewhat better growth of the larvae was introduced by feeding the rice stems cultured in the high phosphorus levels, whereas the difference of larval weights was not significant between high and low phosphorus levels. This result may be due to the high content of nitrogenous compounds found in the rice plant by supplying high level of the phosphate.
From the results of present experiments, it is considered that the application of phosphorus fertilizer on rice plants in an ordinary paddy field has little effect on the growth of the borer larvae
